Rheostat.



D. P. RUGBR.

RHEOSTAT.

APPLICATION FILED JULY 22, 1910.

1,073,173. Patented Sept. 16, 1913;

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l r1 I u l m l y l I l A f a. Z w 1 D. P. RUGER.

RHEOSTAT.

APPLICATION FILED JULY 22, 1910. 1 ,073,1 73. Patented Sept. 16, 1913.

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W Z W @484. W z gggp UNITED STATES rA'rnivr OFFICE.

DUEL P. BUGER, OF CHICAGO, ILLINOIS, ASSIGNOB T0 THOMAS MARSHALL, OF

CHICAGO, ILLINOIS.

RHEOSTAT.

Specification of Letters Patent.

Patented Sept. 16, 1.913.

Application filed July 22, 1910. Serial No. 573,167.

To all whom, it may concern Be it known that I, DURL P. RUGER, a citizenof the United States, residing at Chicago, in the county of Cook andState of Illinois, have invented a certain new and useful Improvement inRheostats, of which the following is a specification.

This invention relates to devices for varying the resistance in anelectric circuit, and has for its object to provide a new and improveddevice of this description.

The invention is illustrated in the accompanying drawing, wherein-Figure 1 is a side elevation of one form of device-embodying theinvention; Figs. 2 and 3 are similar views showing modifiedconstructions wherein one or both elements are divided into a series ofparts; Fig. 4 is a side elevation showing a further modification inwhichan external resistance is used; Fig. 5 is an end view of the deviceshown in Fig. 4; Fig. (3 is an enlarged side elevation of a portion ofthe device shown in Fig. 4; Fig. 7 is a perspective view showing amodified construction in which there are two sets of elements acting asa unit.

Like numerals refer to like parts throughout the several figures.

Referring to Fig. 1, I have shown two cotiperating elements l and 2,adapted to be connected in an electric circuit by the conductors 3 and4. As shown in this figure the elements each consist of a single pieceof conducting material, such as carbon or any other material which willconduct electricity, and which will cause resistance at the point orplace of contact of the two elements. The electric current when thedevice is in use will flow through one conductor, say, the conductor 3,to the element 1, thence to the element 2, and thence through conductor4. The elements 1 and 2 are arranged so that the area of contact betweenthem is smaller than the entire area of their adjacent faces. Thisresult may be secured by making one or both of the elements with a moreor less curved surface, the amount of curvature depending, of course,upon the conditions presented and the results desired. By thisconstruction it will be seen that the elements may be rocked, that is,rolled one upon the other, so as to vary the position of the area' ofcontact between them. The parts may be rocked by hand or in any otherdesired manner. As illustrated in Fig. l, the element 1 is provided witha projecting part 5, having connected therewith a core (5 of a solenoid7, So that the relative position of the elements and 1% may becontrolled bv means of this solenoid. When the core of the solenoid isin its lowest position, the position of the area of contact betweenelements 1 and 2 would be at the edge nearest the solenoid, so that avery small amount of the resistance of said elements is in circuit. Asthe core of solenoid 7 is raised the position of the area of contactbetween elements 1 and2 will move along the surface of said elementsaway from said solenoid, until when the core is in its highest positionthe area of contact will be at the edge of the elements farthest awayfrom the solenoid. During this operation the resistance of elements 1and 2has been gradually introduced into the circuit until at the lastposition all of the resistance is in circuit. It will thus be seen thatany desired amount of the resistance of elements 1 and 2 may be insertedin the circuit, and that the entire variation of the resistance issecured by a very small movement of the projecting part and the core 6of the solenoid. In this construction the position of the area ofcontact between the elements 1 and 2 moves back and forth without acorresponding movement of the elements. The parts may be so constructedthat a very small or limited rocking or rolling of the elements withrelation to each 0tl1el Wlll produce a large range of movement of thisarea of contact with relation to the surfaces of the elements, and thatonly a very small amount of power is necessary to secure this movement.The device may therefore be very easily and efiectively operated.

In Fig. 2 the element 1 consists of a single piece of material, but theelement 2 is made up of a series of pieces of material making resistancecontact with each other as well as with the element 1. The position ofeach of these pieces of element 2 is fixed with respet to the positionof the adjacent pieces.

The construction shown in Fig. is similar to that shown in Fig. 2,except that elein Fig. 5.

ment 1 is also divided up into a number of pieces, the-pieces being ofconducting material held against longitudinal movement with relation toeach other, and making contact resistance with each other.

In Fig. 4 the element 2 is divided into a number of pieces of conductingmaterlal which are electrically connected to each other through anexternal resistance 8, the pieces 9 being separated from each other bythe insulation 10. Each piece 9 is connected by a conductor to theproper point on the external resistance 8, as shown. The parts may beheld together in any desired manner. As herein shown the pieces 9 areheld in proper position by the rods 11, which engage grooves 12 in thesides thereof as shown These rods are passed through the end pieces 13,which are properly insulated from the pieces 9 by the insulating pieces14. The element 1 may also be provided" with similar rods 11 and end'pieces 13 and insulating pieces 14. The projecting part 5 may beconnected to the two projecting parts 15 on the end piece 13, as shown.The'material of one of the elements 1 or 2 of Figs. 4 and 5 must be suchthat there will be substantial resistance between the two elements,non-metallic material such as carbon being the preferred material.

Fig. 6 shows a portion of the device illustrated in Figs. 4 and 5. Theelement 1' is shown in contact with the two adjacent pieces 9 and 9 ofthe element 2. The current now flows from conductor 3 to element 1,thence through contact 9 and then through resistance 8- to conductor 4.If, new, the element 1 is graduall rocked or rolled to the left, thepressure etween element 1 and the piece 9 will gradually decrease, and,since there is resistance between element 1 and the piece 9 thisdecrease in pressure will increase the resistance between them, and thiswill continue until they are no longer in contact, whereupon theresistance between them will be such as to prevent the fiow of current.As this change has been taking place the current flowing from element 1to the piece 9 has gradually been transferred to piece 9 due to the factthat the resistance between the piece 9 and element 1 has beendecreasing while this change has been taking place. When the element 1ceases to contact with the piece 9 the current ceases to flow throughsaid piece, and flows through the piece 9 The current now flows fromconductor 3 to element 1, then through contact 2, thence through theexternal resistance 8 including the section 8 to conductor 4. Thecurrent is now compelled to pass through the additional section 8 of theexternal resistance 8,thus throwing more resistance into circuit. In thesame way the various steps or portions of the external resistance 8 canbe cut into or out of circuit. By increasing the radius of curvature ofthe adjacent surfaces of elements 1 and 2, three or more conductingpieces of element 2 would be in contact with element 1 at one time, butthe action of introducing the external resistance 8 in circuit would besimilar to that herein described, except that the current would bedivided among a greater number of paths.

The-method of operation of the device as shown in Figs. 2 and 3 would besimilar to that described with relation to Figs. 4, 5 and 6, except thatthe external resistance 8 of these latter figures would be replaced bythe resistance between the conducting pieces. The device illustrated inFigs. 4, 5 and 6 is preferable where a greater resistance is desiredthan can be readily obtained through the resistance alone-of theconducting pieces..

In Fig. 7 I have shown a construction where a plurality of elements, 1and 2, are used. In this construction the conductors 3 and 4 may beconnected to the stationary elements, and hence an electric connectionto a moving element avoided. The current will then pass from conductor 3to one element 2, thence to its opposed element 1, thence across to theother element 1, and thence to the opposed element 2, and thence toconductor 4.

It is, of course, evident that the formand construction of the twoelements will depend upon the conditions presented, and the resultsdesired, and that the form of resistance contact may of course bechanged.

provide contact resistance to the passage ofan electric current from oneto the other at the surface of contact-,and a cooperating elementcooperating with said first element, the two elements havingnon-parallel faces when in contact arranged so that the position of thearea of contact between the two elements is varied so as to vary thenumber of said conducting pieces in circuit to vary the resistance.

2. A resistance varying device comprising a resistance element providedwith a series of conducting ieces fixed with relation to each other anmaking contact resistance with each other, and means for varying thenumber of said conducting pieces in circuit.

3. A resistance varying device comprising an element having aseries ofconducting pieces arranged in rows, the conducting pieces of each rowmaking contact resistance with each other, a similar cooperating elementhaving conducting pieces with resistance contact arranged in rows, saidrows opposed to the said rows of the first element,

and means for rolling the two elements to vary the number of conductingpieces in circuit.

4. A resistance varying device comprising an element provided with aseries of carbon strips placed upon end and arranged in rows, the carbonstrips in each row making resistance contact with each other, theseveral rows connected in an electric circuit, a cooperating elementadapted to make contact with a port-ion of said carbon strips, and meansfor varying the position of the area of contact between the two elementsso as to vary the number of carbon strips in circuit.

5. A resistance varying device comprising an element having a series ofcarbon strips arranged in separate rows, the carbon strips in each rowmaking electrical contact with each other, the several rows insulatedfrom each other but connected in an electric circuit in series, acooperating element connected in an electric circuit, the two elementshaving a small area of contact, and means for moving the position of thearea of contact between the two elements back and forth across the faceof said element so as to vary the resistance in the circuit.

(3,. A resistance varying device comprising two resistance cooperatingelements having coacting surfaces of substantially the same length, andmeans for varying the position of the area of contact between saidsurfaces so as to change its location with relation to said elements.

7. A resistance device comprising two elements both made of material ofpoor electrical conductivity and located one above the other and havingcoacting surfaces of substantially the same length, said surfacesarranged so that only a portion is in contact at any given time, andmeans for moving the area of contact along said surfaces so as to changeits location with relation to said elements.

S. A resistance varying device comprising two cooperating elementshaving coacting surfaces of substantially the same length, one of saidelements made up of a series of conducting pieces fixed with relation toeach other and having resistance contact with each other, and means forvarying the position of the area of contact between the coactingsurfaces of said two elements so as to change its location with relationto said elements to vary the number of conducting pieces in circuit.

9. A resistance device comprising two cooperating resistance elementshaving coacting surfaces, a comparatively small portion of said surfacesbeing in contact at a given time, and means for varying the position ofthe area of contact between said surfaces so as to change its locationwith relation to said elements by moving the adjacent ends of saidelements toward and from each other.

10. A resistance varying device compris ing two non-metallic resistanceelements, each element having a face fixed with relation to saidelement, andcooperating with the other element, the fixed faces beingnonparallel so that only a portion thereof can be in contact at onetime.

11. A resistance varying device comprising a non-metallic resistanceelement, having a fixed contact face, a second resistance element havinga cooperating contact face fixed with relation to said latter element,the cooperating face of one or both elements being curved so that only aportion of the cooperating surfaces can be in contact at a given time.

12. A resistance varying device comprising an element having a series ofconducting pieces in proximity to each other, and electrically connectedto each other through electrical resistance, and a coo crating elementcooperating with said rst element, the two elements having non-parallelfaces when in contact, the material used in that portion of the two saidelements where they come in contact being such that there will beresistance contact at the area of contact between them, these twoelements being so arranged that the position of the area of contactbetween the two elements is varied so as to vary the amount ofresistance in circuit.

18. The combination with an electric cir-- of July, 1910.

DURL P. RUGER. Witnesses:

DONALD M. CARTER, EDNA K. REYNOLDS.

mgmaterial, one of which is made of resist-'

